1. Field of the Invention
The present invention relates to a DC-DC converter for issuing a differential voltage, and a switching regulator for passing sink current.
2. Description of the Related Art
Along with diversification of an operating voltage in electronic devices, there is an increasing demand for a DC-DC converter for generating different supply voltages. Recently, for application into interface technology between electronic devices of different supply voltages, not only at the high voltage side of supply voltage but also at the low voltage side, the DC-DC converter issuing differential voltage by setting variably is being demanded.
One of such interface technologies is disclosed, for example, in Japanese unexamined patent publication No. 2002-111470. This technology applies to the semiconductor chip including a plurality of circuit blocks mutually different in an operating supply voltage, and substantially common in a logical threshold voltage. Individual circuit blocks are characterized by using the voltage difference of a low voltage level and a high voltage level as an operating supply voltage, with the logical threshold voltage enclosed between them, and are capable of issuing a signal in an amplitude corresponding to the operating supply voltage, and receiving a signal of other amplitude having the logical threshold voltage enclosed between them.
Japanese unexamined patent publication No. 2002-111470 discloses a voltage generating circuit shown in FIG. 5 for realizing such interface technology. The voltage generating circuit comprises a pair of regulators 111 and 112. The regulator 111 is a source side linear regulator for generating a high voltage level vdd1 on the basis of reference voltage (+) vref1. On the other hand, the regulator 112 is a sink side linear regulator for generating a low voltage level vss1 on the basis of a reference voltage (−) vref1. Accordingly, a high voltage level vdd1 and a low voltage level vss1 enclosed by the high voltage level vcc and the low voltage level gnd of the operating supply voltage in a semiconductor chip can be supplied as power source to a circuit block BLK1.